Claude Opus 5 (Fast)

Claude Opus 5 belongs to Anthropic's 2026 Claude 5 family of frontier models, released on July 24, 2026 alongside siblings Fable 5, Mythos 5, and Sonnet 5. It is positioned as the top-of-line Opus variant, designed for high-stakes reasoning tasks where depth of analysis matters more than raw throughput. Anthropic's broader Opus line has historically targeted complex coding, research synthesis, and multi-step agent workflows, and Opus 5 continues that role with the freshest knowledge window of any Claude model at the time of launch.

According to independent reporting, Opus 5 is reported to roughly double the prior Opus 4.8 score on Frontier-Bench v0.1 and to land within half a percent of the flagship Fable 5's peak on CursorBench 3.2 while costing half as much, with similar relative gains reported on OSWorld 2.0. A "Fast" routing variant like this one is typically tuned to preserve that reasoning quality while trading some peak capability for faster response times, making it well suited to interactive agent loops, iterative coding assistance, and tool-heavy pipelines where latency matters more than squeezing out the last fraction of benchmark accuracy.